Three-dimensional imaging is increasingly becoming more relevant to security applications, such as, for example, for facial recognition in both the public and private sectors. Three-dimensional facial recognition can exploit the relative insensitivities of three-dimensional facial shape images to facial color variations and facial illumination changes versus traditional two-dimensional images. Triangulation is one method typically used to acquire a three-dimensional image of an object at short range.
Some commercially available three-dimensional image capturing systems employ passive or texture-assisted stereo imaging or structured illumination with a moving light stripe. These techniques, however, require a stationary subject. For example, one traditional method of triangulation uses an active light that translates a line and/or line pattern across an object and recovers the three-dimensional profile at each position based on the deformation of the line in the image. This process requires the calibration of both the line projector and the motion platform. Still another example method utilizes a single camera, a single laser line projector, and a controlled conveyor belt to image objects by assembling a series of two-dimensional profiles obtained by object displacement. This process similarly requires moving parts as well as calibration between movement of the object and the camera.